A field test of a model for the stability of androdioecy in the freshwater shrimp, Eulimnadia texana

The evolution of hermaphroditism from dioecy is a poorly studied transition. Androdioecy (the coexistence of males and hermaphrodites) has been suggested as an intermediate step in this evolutionary transition or could be a stable reproductive mode. Freshwater crustaceans in the genus Eulimnadia have reproduced via androdioecy for 24+ million years and thus are excellent organisms to test models of the stability of androdioecy. Two related models that allow for the stable maintenance of males and hermaphrodites rely on the counterbalancing of three life history parameters. We tested these models in the field over three field seasons and compared the results to previous laboratory estimates of these three parameters. Male and hermaphroditic ratios within years were not well predicted using either the simpler original model or a version of this model updated to account for differences between hermaphroditic types ('monogenic' and 'amphigenic' hermaphrodites). Using parameter estimates of the previous year to predict the next year's sex ratios revealed a much better fit to the original relative to the updated version of the model. Therefore, counter to expectations, accounting for differences between the two hermaphroditic types did not improve the fit of these models. At the moment, we lack strong evidence that the long-term maintenance of androdioecy in these crustaceans is the result of a balancing of life history parameters; other factors, such as metapopulation dynamics or evolutionary constraints, may better explain the 24+ million year maintenance of androdioecy in clam shrimp.

Comparison of an inertial sensor system of lameness quantification with subjective lameness evaluation

REASONS FOR PERFORMING STUDY

Subjective evaluation of mild lameness has been shown to have poor interobserver reliability. Traditional methods of objective lameness evaluation require specialised conditions and equipment. Wireless inertial sensor systems have been developed to allow for simple, rapid, objective lameness detection in horses trotted over ground.

OBJECTIVE

The purpose of this study was to compare the sensitivities of an inertial sensor system and subjective evaluation performed by experienced equine practitioners at detecting lameness in horses. We hypothesised that the inertial sensor system would identify lameness at a lower level of sole pressure than a consensus of 3 experienced equine veterinarians.

METHODS

Fifteen horses were fitted with special shoes that allowed for lameness induction via sole pressure. Horses were simultaneously evaluated by 3 equine veterinarians and a wireless inertial sensor system. Horses were subjected to multiple trials: 1) before inserting the screw; 2) after inserting the screw to just touch the sole; and 3) after tightening the screw in half turn increments. The number of screw turns required for lameness identification in the correct limb by the inertial sensors and by consensus of 3 equine veterinarians was compared using the Wilcoxon test.

RESULTS

The inertial sensor system selected the limb with the induced lameness after fewer screw turns than did the 3 veterinarians (P<0.0001). The inertial sensor system selected the correct limb before the 3 veterinarians in 35 trials (58.33%), the evaluators selected the correct limb before the inertial sensors in 5 trials (8.33%), and in 20 trials (33.33%) they selected the correct limb at the same time.

POTENTIAL RELEVANCE

The inertial sensor system was able to identify lameness at a lower level of sole pressure than the consensus of 3 equine veterinarians. The inertial sensor system may be an effective aid to lameness localisation in clinical cases.

Theoretical and computational study of high-pressure structures in barium

Recent high-pressure work has suggested that elemental barium forms a high-pressure self-hosting structure (Ba IV) involving two "types" of barium atom. Uniquely among reported elemental structures it cannot be described by a single crystalline lattice, instead involving two interpenetrating incommensurate lattices. In this Letter we report pseudopotential calculations demonstrating the stability and the potentially disordered nature of the "guest" structure. Using band structures and nearly free electron theory we relate the appearance of Ba IV to an instability in the close-packed structure, demonstrate that it has a zero energy vibrational mode, and speculate about the structure's stability in other divalent elements.

A mental health capitation program: I. Patient outcomes

OBJECTIVE

The Monroe-Livingston demonstration project's capitation payment system (CPS) was evaluated to determine whether capitated funding of mental health care, compared with fee-for-service funding, could reduce hospitalization rates and improve functioning and symptoms for severely and persistently mentally ill adults without increasing the total cost of care.

METHODS

The experiment was a communitywide prerandomized clinical trial involving 422 patients. Patients who were randomized into the experimental group were eligible for enrollment in a capitated funding program administered by one of five community mental health centers. Those randomized into the control group received standard fee-based services. Follow-up interviews with patients one and two years after enrollment in the study assessed changes in symptoms and functioning. Data files of the membership corporation that coordinated community mental health services for the CPS provided measures of study patients' use of inpatient mental health services.

RESULTS

During the two-year follow-up period, patients in the experimental group had significantly fewer hospital inpatient days than patients in the control group, but the two groups had no significant differences in functioning or level of symptoms.

CONCLUSIONS

The CPS successfully maintained severely ill patients in the community but did not improve their functioning or level of symptoms.

A mental health capitation program: II. Cost-benefit analysis

OBJECTIVE

Total monetized and nonmonetized costs and benefits to society of the Monroe-Livingston demonstration project's capitated payment system (CPS) were analyzed.

METHODS

Total costs and benefits of care for individuals who were prerandomized to an experimental group (of whom about 57 percent were enrolled in the CPS) were compared with those for a control group who received traditional fee-for-service care. Separate two-year results are presented for continuous patients, who were enrolled in a comprehensive CPS plan (N = 201) and for intermittent patients, who were enrolled in a partial plan (N = 155).

RESULTS

All groups showed improvements on many psychosocial measures over the two years. Continuous patients in the experimental group experienced less hospitalization, more case management and transportation services, and higher levels of victimization and were more likely to live in unsupervised settings than continuous patients in the control group. Total annual per patient costs for care of continuous patients ranged from $74,000 to more than $100,000, largely reflecting differences in rates of hospitalization. Experimental subjects in the partial capitation condition differed from the control group in this plan on fewer measures; both groups reported high levels of case management and social support services and relatively lower levels of supervised housing.

CONCLUSIONS

The CPS resulted in major improvements in the community's services for persons with serious mental illness and reduced the proportion of care provided in the state hospital.

Serious mental illness and capitation financing

Traditional organization and financing of mental health care has not adequately served the needs of persons with serious mental illness. Capitation financing is being tested in several localities, but little experimental data has been yielded to date, and it is mixed. The results from the Rochester experiment were positive but limited, and some other pilots also reported positive experiences with capitation. Others have ended prematurely or confronted obstacles. Experimental findings are also anticipated from the Philadelphia and California pilots, and others are just beginning. Existing financing mechanisms, cost-shifting efforts, and professional cultures represent powerful obstacles to successfully implementing capitation financing for care of persons with long-term mental illnesses, and potential incentives to underserve enrollees require adequate accountability structures. In spite of obstacles, the goodness of fit between the needs of persons with serious mental illness and capitation flexibility warrant further exploration of this financing modality.

Methodology for evaluating the Monroe-Livingston capitation system

This paper presents the methodology for evaluating the Monroe-Livingston demonstration project's capitation payment system (CPS), based in Rochester, New York, for chronic mentally ill patients. To allow for both patient and provider choice within the experimental design, 1,587 CPS-eligible patients were randomly assigned at the start of the study to control or experimental conditions, with the intent of capturing in the experimental group a significant number of patients who would later be enrolled in the CPS. Protocols, which included measures of symptomatology, functioning, and resource utilization, were completed at baseline for 422 of the 605 patients contacted for inclusion in the study. The baseline control group included 143 patients; the experimental group included 279 patients, 153 of whom were eventually enrolled in the CPS.

Selecting analogous problems: similarity versus inclusiveness

Students were asked to select one of two analogous problems in order to solve algebra word problems. In Experiment 1, one problem was less inclusive and the other was more inclusive than a test problem. The students judged the complexity and similarity of problems, selected analogous problems, and used the solutions to solve test problems. They performed significantly better on the test problems when given the more inclusive solutions, but used perceived similarity rather than inclusiveness to select analogous problems. The same pattern of results occurred in Experiment 2, in which isomorphic problems replaced the more inclusive problems. The results show that students are deficient in selecting good analogies, both from the same category (Experiment 1) and from a different category (Experiment 2). Students who saw the analogous solutions (Experiment 3) or were majoring in mathematics (Experiment 4) were more likely to select an isomorphic problem over a less inclusive problem, but were not more likely to select a more inclusive over a less inclusive problem.

Separate ribosomal pools in sea urchin embryos: ammonia activates a movement between pools

Monoribosomes from unfertilized eggs of Strongylocentrotus purpuratus were shown to translate mRNA less efficiently than ribosomes derived from polyribosomes of embryos, as measured by globin synthesis in a ribosome-dependent rabbit reticulocyte lysate [Danilchik, M. V., & Hille, M. B. (1981) Dev. Biol. 84, 291-298]. Data presented in this paper show that monoribosomes from 16-cell and blastula embryos resemble monoribosomes from unfertilized eggs in translational capacity and are less active than the ribosomes associated with polyribosomes. Thus, we find two distinct populations of ribosomes in embryos. We define the less active monoribosome population as "naive" ribosomes and the more active, functioning polysome-derived ribosomes as "experienced" ribosomes. Naive and experienced ribosomes have the same elongation rates. The relationship between ionic triggers and the conversion of monoribosomes to experienced ribosomes was studied with the Ca2+ ionophore A23187, which releases intracellular Ca2+ stores, and NH4Cl, which alkalinizes the cytoplasm. We found that ribosomes in the monoribosome populations from A23187-activated eggs or from NH4Cl-activated eggs resembled naive monoribosomes from unfertilized eggs in their translational activity. In contrast, ribosomes derived from the polysomes of NH4Cl-treated eggs were as active as the experienced polysome-derived ribosomes from normal embryos. Eggs activated with A23187 did not produce polyribosomes. The presence of significant amounts of experienced ribosomes in NH4Cl-treated eggs implicates alkalinization of the cytoplasm as a stimulus for ribosome activation, which occurs slowly during initial development.

The epidemiology of treatment for chronic and nonchronic mental disorders

To estimate the annual treated incidence and prevalence of chronic and nonchronic mental disorders, data from the Monroe County Psychiatric Register were analyzed. Patients were classified as either chronic or nonchronic based upon their utilization of inpatient psychiatric treatment. A chronic illness was defined as one requiring at least three psychiatric hospitalizations or at least 365 inpatient days during a 5-year follow-up period. Based upon this definition, the annual treated incidence of chronic mental disorders did not change significantly between 1964-65 (.47/1000) and 1969-70 (.41/1000), unlike the annual treated incidence of nonchronic disorders, which rose by 37 per cent (p less than .001). The annual treated prevalence of chronic mental disorders also remained unchanged at approximately .6 per cent between 1965 and 1970, but the treated prevalence of nonchronic mental disorders rose by 43 per cent from 1.4 per cent in 1965 to 1.9 per cent in 1970 (p less than .01). These increases in treatment for nonchronic disorders coincided with the development of community mental health centers. The rates of chronicity and peak ages of treatment varied considerably across diagnostic groups. Approximately one fifth of new cases of organic brain disorders, schizophrenia, and alcohol disorders became chronic according to our definition during the first 5 years after illness onset, compared to only 9 to 11 per cent of cases of major affective disorders and less than 2 per cent of all other disorders.(ABSTRACT TRUNCATED AT 250 WORDS)

Priorities for long-term care: comments from board-and-care residents

In these times of shrinking human services resources, establishing clear service priorities becomes all the more necessary. This is particularly true for the care of chronically mentally ill persons, whose many needs place high service demands on the care system. As a group these patients rarely have a say in the establishment of service priorities. To obtain a better idea of their perceived needs, we asked 278 randomly selected, mentally disabled residents in 30 Los Angeles board-and-care homes about their current life conditions and problems. Their responses to open-ended questions about recent sources of unhappiness and desired changes were compared with quantitative measures of life satisfaction in several life areas. Unemployment, poverty, and housing were the areas in which patients most consistently expressed dissatisfaction and desire for change. Also, mental health problems, including interpersonal and family difficulties, caused frequent day-to-day unhappiness for them. These findings underscore the need for social service programs that adequately address patients' problems of living, in addition to continuing efforts to meet their mental health needs.

Production and activity of the Kav 0.64 pheromone fraction of Nippostrongylus brasiliensis

The pheromone fraction that elutes at Kav 0.64 in gel filtration showed significantly reduced activity for the male's locomotor response when obtained from 10-day-old, or older, female Nippostrongylus brasiliensis. This fraction, obtained from males and females that were admixed prior to extraction, revealed a sex-ratio dependent increase in pheromone activity at 50%:50% male:female according to the male's locomotor response. The female's response to mixed sex pheromone at Kav 0.64 showed no distinct sex-ratio effect. The pheromone that was contained within the female helminths as the Kav 0.64 elutant exhibited little variation in its level, based on collection period studies up to 3 hr. However, exposure of females to male worms altered the amount of pheromone at Kav 0.64 that was recovered from maceration and gel filtration of female helminths, presumably owing to pheromone release.

Structural models and embedded-figure difficulty for normal and retarded children

60 normal and 20 mentally retarded children were tested on an embedded-figures task to determine what stimulus variables correlate with the difficulty of finding a figure hidden in a larger pattern. The number of shared contours, the complexity of the ground, and analysis complexity (defined as the amount by which the total complexity of the parts exceeds the complexity of the whole pattern) resulted in significant, positive correlations with the difficulty of finding an embedded figure. The complexity of the figure, the complexity of the complete pattern, and the number of overlapping lines resulted in nonsignificant, positive correlations with the difficulty in finding the figure. The task was discussed within the theoretical framework of the structural model advocated by Narasimhan and Sutherland. The results suggested how a pattern might be analyzed into a hiearchy of articulations with each articulation consisting of a hierarchy of component parts.